Chronic renal insufficiency (CRI) and cognitive impairment are common diseases in the elderly, both associated with increased health-care utilization and decreased quality of life. Whether CRI is associated with accelerated cognitive aging over time has not been addressed. We have preliminary cross-sectional evidence that CRI may be associated with cognitive impairment in the elderly, but no prospective studies have been conducted on the relationship between CRI and cognitive outcomes. If such an association can be established, the clinical care of patients could be directly influenced by screening for cognitive impairment, more close monitoring of treatment adherence and the use of drugs and other strategies to improve cognition. The goals of this proposal are to investigate whether severity of CRI is associated with greater cognitive decline in older individuals with CRI, to assess whether the relation between CRI and cognitive function is modified by targeted demographic and clinical factors, and to examine potential mechanisms of cognitive decline, such as cardiovascular disease and inflammation. Our aims will be addressed as an ancillary study to the ongoing NIDDK-funded Chronic Renal Insufficiency Cohort (CRIC) study. This prospective study will examine the epidemiology and outcomes of CRI in a large, representative population of patients with CRI. Among 720 older CRIC participants who enroll in the proposed CRIC Cognitive Function Ancillary Study, we will cost-efficiently 1) determine the association between CRI and 3-4 year cognitive decline among CRIC participants over age 55 years; 2) evaluate whether the association between CRI and cognitive decline is consistent among different patient subgroups such as those of different races and ethnicities, and those with and without diabetes mellitus; 3) elucidate several mechanisms that may mediate the association between CRI and cognitive decline, including cardiovascular disease and inflammation. Assessing the nature of cognitive impairment in a representative population with CRI will provide crucial data for determining the burden of disease and health care needs of those with CRI. Moreover, understanding these relations may help to identify potential modifiable risk factors and to treat cognitive impairment thereby maintaining independence among patients with renal disease